| October 05, 2010 |
How to inspect a used small dozer
By Marcia Gruver
Good used machines are at a premium these days, so it was the luck of the draw that we got to inspect not one, but two small dozers at the Tractor & Equipment yard in Birmingham, Alabama. Sitting side by side were a Komatsu 78-horsepower D31PX-22 with 500 hours and a 110-horsepower D41E-6C with 1,400 hours. Calling on his more than 30 years experience, Larry D. Foltz, district manager for Komatsu America, gave us an overview of both machines, and started out the inspection by verifying their serial numbers and hours. Next up: the walk around.
Machine inspections start with a walk around, which allows you to get an overall sense of the machine’s condition. First, note what’s on the dozer. What kind of blade does it have? Is there a winch or a ripper? Is the ROPS open or enclosed? Both of our machines had a power angle tilt blade with an open canopy. If either of them had had a ripper or an enclosed cab, the final price would have been adjusted upward.
As you walk around the machine, look for any structural problems. Examine the main frame, track frames, hood, sheet metal panels, grill, fuel tank and paint condition. You’re looking for dents, punctures, extreme scraping and evidence of welding or plating.
Examine all blade cylinders, hoses and pins. Are any of the cylinders dented or damaged? Has the chrome on the cylinder rods been scratched? If so, leaks will either be already present or eminent. If oil can get out, dirt can get in. Next, check the blade itself – are there any welds or cracks? Are the edges worn – if so, can they be turned? Are the blade pins and bushings tight? Any patches, visible cracks, welds or plates on the push arms? Check the trunnion or pivot point for wear. Are shims available to allow for adjustment? Do the blade grease points show signs of recent greasing?
Obvious signs of abuse on a dozer center around the blade and undercarriage, Foltz says. If you see punctures in the skin of the blade, or it’s ripped or indented, it may be a sign that it’s been pushing another machine or working in severe rock. “The external appearance on a machine will tell you a lot,” he says. “I’ve seen machines come in with no grab handles, knocked off guarding around the lights, bolts missing or engine hood covers are damaged or broken. Heavy rock applications or situations where contractors used too small of a dozer for the application will make the machine show advanced signs of wear.”
As expected due to their relatively low hours, both the D31 and D41 came away looking relatively unscathed, although Foltz says the hour meter doesn’t always tell the whole story. “I’ve seen machines with just 500 hours on them that were significantly beat up,” he says. “It’s all in the application it’s been used in.”
Climb into the cab and take a close look at the condition of the ROPS, seat, seat belt, floorboards and mats, instrument panel and controls. If your unit has an enclosed cab, examine the doors, latches and all glass. Note the state of the steps, handrails and mirrors.
As you walk around the dozer, look for leaks on the cylinders and final drives, and for any engine or transmission leaks underneath the machine. “Neither machines have any visible signs of final drive leakage on the inside of the tracks,” Foltz says. Then inspect all interior compartments – engine, battery and hydraulic – for leaks. Foltz noted the battery covers were in place on both machines and all connections were tight.
Check all fluid levels, including engine oil and coolant, before you start the engine. “You don’t want to start something up that’s low on oil and blow an engine,” Foltz comments. Take oil samples of the engine, transmission and hydraulic oils. The 500-hour D31 is right at the point where the engine oil and filter would need to be changed. And check the dipstick for water, which could mean an internal water leak. While you’re in the engine compartment, check the engine belt and tension. Examine the air filter.
“Check for hydraulic leaks on hoses and fittings,” Foltz says. Also look for cylinder rod damage, and leaks in the cylinders, valves, pumps and motors.
Turn on the dozer and listen to the engine. Does it start easily? Are there any unusual noises either from the engine or the turbocharger? Check the oil pressure.
Operate the machine, putting it through its paces. How easily does it steer left/right, and travel in forward/reverse? On dozers such as our review models with hydrostatic transmissions, listen for transmission noise and note vibration – too much of either could mean worn pumps or motors.
Check out the electrical system: warning lights, gauges, batteries, work lights and monitor panel. If the cab is enclosed, make sure the heat and air conditioning works properly. Note whether the backup alarm works.
Operate all blade functions (angling, right/hold/left; tilting, right/hold/left; and lifting, raise/hold/lower/float). “When you work the blade, look for any looseness,” Foltz says. Is there any drifting movement after the blade has been stopped?
As you operate the brakes, make sure there’s no grabbing or excessive noise. Also see if the machine brakes and steers left and right equally and thoroughly. And operate the parking brake.
Although it’s difficult to do in some buying situations, you should be able to operate the dozer under load to truly assess its condition. “Make sure it has the power to handle the load,” Foltz comments.
“The undercarriage represents the potentially highest expense you’ll encounter on a used dozer,” Foltz says. On dozers the size of our inspection machines, a new undercarriage would cost in the neighborhood of $12,000 to $15,000. “Over the life of a dozer,” he says, “you can expect to pay about as much in replacement undercarriage costs as you originally paid for the dozer when it was new.”
Determining undercarriage wear is critical to determining the final price of used dozer – so much so, an outside undercarriage inspection that determines the exact wear left on each undercarriage component is key. This assessment should tell you a number of things, including the percentage wear (compared with new) on these undercarriage components on each side of the machine:
• Rails, including number of links and type (wet or dry)
• Track pins and bushings
• Carrier rollers
• Track pads, including pad width and type, grouser height, and whether there’s any scalloping
• Front idlers
• Rear idlers (if high drive)
• Bottom rollers
These measurements can be either done manually with a caliper and measuring tape, or with a sonic measuring device that works by placing the device on a component to determine the thickness of the steel. The device then references the measurements in the machine’s service manual to calculate the percentage of wear left. However it’s done, this assessment will run you about $200 to $300, says Lee Haak, Komatsu Remarketing, so it should only be performed on machines you’re serious about. “Since each manufacturer’s dealer has access to their own reference materials, I’d have the OEM dealer for the particular model you’re considering buying do this undercarriage inspection report,” he says.
Machines such as our demonstration units (the oldest with 1,400 hours) should not have totally new undercarriages. If they do, it might be a sign of abuse or use in a severe application. Foltz determined the older D41 would probably require an undercarriage replacement within 300 to 400 hours, so that would need to be factored into that unit’s price.
Another key in determining remaining undercarriage life is finding out how the machine has been used. A machine working in sand or rock, for instance, will have a much different wear rate than one working in loam.
An additional wear factor is track tightness. Tracks are designed for a certain amount of looseness to account for packed dirt and other material. Some dozer owners, however, run their tracks too tight, resulting in two to three times the internal wear rate on the pins, bushings and idlers. “Look for evidence of mud packing in the sprockets and the link assemblies,” Foltz says.
Seasoned professionals can get an initial assessment by reaching in and feeling the wear on the pins and bushings. “When an undercarriage is worn, you can feel a grove worn in the bushing that indicates wear,” Foltz says. “With today’s sealed and lubricated undercarriages, though, most of the wear is external.”
Get the dozer’s repair and maintenance history, noting who the previous owner was, and their maintenance program. Foltz asks for this after his inspection “because I want to give a machine a good unbiased opinion.” Look into whether or not the machine was on a scheduled preventive maintenance program. Also be sure to ask for the oil analysis history.
Now’s the time to do some basic math. Sit down with your notes (our handy checklist at the end of this article will help keep them organized) and go through each inspection point, either downgrading or upgrading the unit under consideration. This will give you either a final ballpark figure or convince you to pass on this particular machine if it has too many problem areas. EW
Small dozer inspection checklist
Cab or open ROPS?
Oil analysis results on engine,
transmission and hydraulic systems:
Initial walk around
Oil levels: Low or over full?
Do all fittings take grease?
Cracked or welded?
All doors and latches working?
Condition of glass, seat and floorboards/mat
Does the AC/heat work?
Frame/sheet metal/grill damage?
Fuel tank/belly pan damage?
Cracked or welded?
Dozer blade pins and bushings tight?
Patches, welds or plates?
Diagonal brace caps
Welds or bolts missing?
Trunnions and caps wear?
Cutting edge/bits – can it be turned
Condition of other attachments
(rippers, scarifiers, etc.)
Check out warning lights, gauges, battery (need charging or replacing?), work lights and monitor panel
Oil or water leaks?
Belt condition and tension
Turbocharger, leaks or unusual noises?
Operate the machine, checking out steering, brakes, travel and reverse.
Brakes grabbing or noisy?
Does the parking brake work?
Final drive leaks?
Torque converter leaks?
Cylinder rod condition
Cylinder leaks or drifting?
Blade operation (observe the following for any problems)
Measure the following:
Track shoe grouser height
Bushings: Wet or dry?
Can be turned?
Track roller: Seals leaking?
Can be rebuilt?
Can be rebuilt?
Track frame cracked or welded?
Idler wear bars – need replacement?
Working condition of backup alarm, seat belt, fan finger guards, ROPS, neutral start switch, steps and handrails, mirrors and horn
More From: Maintenance
Do you want some tips to stay safe on the job site?
Equipment World has created an entire section devoted to safety.
Here are the most recent tips we've posted: